Co-author Dr. Robert Cantu tells The Boston Globe the study should convince doubters that CTE is a real condition caused by repeat head injuries.

Cantu's colleague, Dr. Ann McKee, told CBSNews.com in July that CTE can only be detected after death by staining tau protein deposits in brain tissue - a complex, several-month process that she compared to developing a photograph.

In September, the NFL announced a donation of $30 million for medical research to the Foundation for the National Institutes of Health, the fundraising arm of the NIH.

NFL Commissioner Roger Goodell said the research could benefit athletes and potential areas of study may include CTE, concussion management and treatment and disorders from later in life such as Alzheimer's.

Last month, Goodell talked to "CBS This Morning" about the growing concerns surrounding the safety of players (watch video at left).